If your inventory is showing as 0 in the warehouse but you are still receiving orders from Walmart, the possible reason could be that you have stock in your secondary warehouse, which is configured in your Walmart portal.

To address this issue and ensure accurate inventory reporting, it is recommended to zero out the inventory in the secondary facility or warehouse. By doing so, Inventory Ahead will only report the inventory from a single warehouse, eliminating any discrepancies.

See informative article here on where to locate your secondary warehouse in Walmart.